With the scaling down of semiconductor devices, new materials with high dielectric constant are required. Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) have become the main deposition techniques for such thin films. CVD and ALD may provide different films (metal, oxide, nitride, etc.) having a finely defined thickness and high step coverage. In CVD and ALD, the precursor molecule plays a critical role to obtain high quality films with high conformality and low impurities.
Among high-k dielectrics, titanium based materials, such as TiO2, are very promising, whether used as pure or mixed oxides or in laminates. TiN may be used for electrode and/or Cu diffusion barrier applications. Titanium oxides may also be used for their etch resistance properties in lithography applications, such as for hard masks or spacer-defined multiple patterning applications. Titanium silicides may serves as a contact between conductive plugs and the underlying doped silicon layer.
Synthesis and characterization of a variety of titanium halide Lewis adducts is known. See, e.g., Ruff et al., New titanium compounds, Berichte der Deutschen Chemischen Gesellschaft, 1912, 45, pp. 1364-1373;    R. Höltje, Zeitschrift fuer Anorganische und Allgemeine Chemie, 1930, 190, pp 241-256;    Emeléus et al., Complexes of Titanium and Zirconium Halides with Organic Ligands, J. Chemical Society (Resumed), 1958, pp. 4245-50;    Fowles et al., Journal of Chemical Society (Resumed), 1959 pp. 990-997;    G. W. A. Fowles et al., The Reaction of Titanium Halides with Tertiary Amines, Journal of Chemical Society (Resumed), 1963, pp. 33-38;    Baker et al., Sulphur Complexes of Quadrivalent Titanium, Journal of the Less-Common Metals, 1964, pp. 47-50;    Eric Turin et al., Adducts of Titanium Tetrahalides with Neutral Lewis Bases. Part I. Structure and Stability: a Vibrational and Multinuclear NMR Study, Inorganica Chimica Acta, 134 (1987) pp. 67-78;    U.S. Pat. No. 5,656,338 to Gordon discloses chemical vapor deposition of titanium metal by forming a liquid solution of titanium tetrabromide in bromine, vaporizing the solution and contacting the vapor mixture with plasma in the vicinity of the substrate;    U.S. Pat. No. 6,706,115 to Leskelä et al. discloses methods for producing metal nitride thin layers have low resistivity by means of atomic layer deposition processes comprising alternate surface reactions of metal and nitrogen source materials; and    U.S. Pat. App. Pub. No. 2010/0104755 to Dussarrat et al. discloses methods for producing a metal-containing film by introducing a metal source which does not contain metal-C or metal-N—C s-bonds, a silicon precursor, a nitrogen precursor, a carbon source and a reducing agent into a CVD chamber and reacting same at the surface of a substrate to produce a metal containing film in a single step.
Synthesis and characterization of a variety of mixed titanium halo alkylamino derivatives is also known. See, e.g., Von Hans Bürger et al., Dialkylamino-titanbromide, Zeitschrift für anorganishce und allgemeine Chemie, Band 370, 1969, pp. 275-282;    Von Hans Bürger et al., Dialkylamido-titaniodide, Zeitschrift für anorganishce und allgemeine Chemie, Band 381, 1971, pp. 198-204;    US Pat App Pub No. 2005/0042888 to Roder et al. discloses metalorganic precursors of the formula (R1R2N)a-bMXb, wherein M is the precursor metal center, selected form the group of Ta, Ti, W, Nb, Si, Al, and B; a is a number equal to the valence of M; 1≤b≤(a−1); R1 and R2 can be the same as or different from one another and are each independently selected from the group of H, C1-C4 alkyl, C3-C6 cycloalkyl, and Rº3Si, where each Rº can be the same or different and each Rº is independently selected from H and C1-C4 alkyl; and X is selected from the group of chlorine, fluorine, bromine and iodine.
FR Pat. App. Pub. No. 2871292 to Dussarrat discloses injection of a metallic precursor having the formula MX4 or MX5, wherein M is preferably Hf, an oxidant and of tetrakis(ethylamino)silane under temperature and pressure conditions that improve the reactivity of the silicon source.
A need remains for thermally stable, volatile, and preferably liquid Ti-containing precursors capable of providing controlled film thickness during vapor phase deposition at high temperature.